from __future__ import annotations

import logging
from typing import TYPE_CHECKING, Dict, List, Optional

from langchain.schema import (
    BaseChatMessageHistory,
)
from langchain.schema.messages import (
    BaseMessage,
    _message_to_dict,
    messages_from_dict,
    messages_to_dict,
)

if TYPE_CHECKING:
    from boto3.session import Session

logger = logging.getLogger(__name__)


class DynamoDBChatMessageHistory(BaseChatMessageHistory):
    """Chat message history that stores history in AWS DynamoDB.

    This class expects that a DynamoDB table exists with name `table_name`

    Args:
        table_name: name of the DynamoDB table
        session_id: arbitrary key that is used to store the messages
            of a single chat session.
        endpoint_url: URL of the AWS endpoint to connect to. This argument
            is optional and useful for test purposes, like using Localstack.
            If you plan to use AWS cloud service, you normally don't have to
            worry about setting the endpoint_url.
        primary_key_name: name of the primary key of the DynamoDB table. This argument
            is optional, defaulting to "SessionId".
        key: an optional dictionary with a custom primary and secondary key.
            This argument is optional, but useful when using composite dynamodb keys, or
            isolating records based off of application details such as a user id.
            This may also contain global and local secondary index keys.
    """

    def __init__(
        self,
        table_name: str,
        session_id: str,
        endpoint_url: Optional[str] = None,
        primary_key_name: str = "SessionId",
        key: Optional[Dict[str, str]] = None,
        boto3_session: Optional[Session] = None,
    ):
        if boto3_session:
            client = boto3_session.resource("dynamodb")
        else:
            try:
                import boto3
            except ImportError as e:
                raise ImportError(
                    "Unable to import boto3, please install with `pip install boto3`."
                ) from e
            if endpoint_url:
                client = boto3.resource("dynamodb", endpoint_url=endpoint_url)
            else:
                client = boto3.resource("dynamodb")
        self.table = client.Table(table_name)
        self.session_id = session_id
        self.key: Dict = key or {primary_key_name: session_id}

    @property
    def messages(self) -> List[BaseMessage]:  # type: ignore
        """Retrieve the messages from DynamoDB"""
        try:
            from botocore.exceptions import ClientError
        except ImportError as e:
            raise ImportError(
                "Unable to import botocore, please install with `pip install botocore`."
            ) from e

        response = None
        try:
            response = self.table.get_item(Key=self.key)
        except ClientError as error:
            if error.response["Error"]["Code"] == "ResourceNotFoundException":
                logger.warning("No record found with session id: %s", self.session_id)
            else:
                logger.error(error)

        if response and "Item" in response:
            items = response["Item"]["History"]
        else:
            items = []

        messages = messages_from_dict(items)
        return messages

    def add_message(self, message: BaseMessage) -> None:
        """Append the message to the record in DynamoDB"""
        try:
            from botocore.exceptions import ClientError
        except ImportError as e:
            raise ImportError(
                "Unable to import botocore, please install with `pip install botocore`."
            ) from e

        messages = messages_to_dict(self.messages)
        _message = _message_to_dict(message)
        messages.append(_message)

        try:
            self.table.put_item(Item={**self.key, "History": messages})
        except ClientError as err:
            logger.error(err)

    def clear(self) -> None:
        """Clear session memory from DynamoDB"""
        try:
            from botocore.exceptions import ClientError
        except ImportError as e:
            raise ImportError(
                "Unable to import botocore, please install with `pip install botocore`."
            ) from e

        try:
            self.table.delete_item(Key=self.key)
        except ClientError as err:
            logger.error(err)
